Music can be soothing or stirring, it can make us dance or make us sad. It triggers especially powerful physical reactions in pregnant women, researchers said.

Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany have discovered that pregnant women compared to their non-pregnant counterparts rate music as more intensely pleasant and unpleasant, associated with greater changes in blood pressure.

Music appears to have an especially strong influence on pregnant women, a fact that may relate to a prenatal conditioning of the foetus to music, said researchers.

For their study, researchers played short musical sequences of 10 or 30 seconds' duration to female volunteers.

They changed the passages and played them backwards or incorporated dissonances. By doing so, they distorted the originally lively instrumental pieces and made listening to them less pleasant.

The pregnant women rated the pieces of music slightly differently, they perceived the pleasant music as more pleasant and the unpleasant as more unpleasant.

The blood pressure response to music was much stronger in the pregnant group.

Forward-dissonant music produced a particularly pronounced fall in blood pressure, whereas backwards-dissonant music led to a higher blood pressure after 10 seconds and a lower one after 30 seconds.

"Thus, unpleasant music does not cause an across-the-board increase in blood pressure, unlike some other stress factors," said Tom Fritz from the Max Planck Institute.

"Instead, the body's response is just as dynamic as the music itself," said Fritz.

According to the results, music is a very special stimulus for pregnant women, to which they react strongly.

"Every acoustic manipulation of music affects blood pressure in pregnant women far more intensely than in non-pregnant women," said Fritz.

Why music has such a strong physiological influence on pregnant woman is still unknown.

"Either oestrogen levels are generally too low in non-pregnant women, or other physiological changes during pregnancy are responsible for this effect," said Fritz.

The researchers suspect that foetuses are conditioned to music perception while still in the womb by the observed intense physiological music responses of the mothers.

From 28 weeks, at the start of the third trimester of pregnancy, the heart rate of the foetus already changes when it hears a familiar song. From 35 weeks, there is even a change in its movement patterns.